Slit-edged ribbons start as one big piece of fabric&period; The fabric is fed into a slitting machine&comma; which slits the fabric into different widths of "ribbon&period; " Usually&comma; the slitting knives are heated so the edges of the ribbon are melted just enough to prevent fraying&period; There is also an ultrasonic slitting machine&comma; which actually cuts and fuses the edges using sound waves&period; Some people call these types of ribbons "fused-edge ribbons"&period;